Polysilicate or other inorganic oxide networks and particles can be generated from molecular precursors through room temperature hydrolytic and condensation sol-gel reactions. Such reactions generally require cosolvents for the essential reactants water and the molecular precursor compound, such as a tetraalkoxysilane, and are catalyzed by either acid or base.
U.S. Pat. No. 5,441,718 describes a process for making an inorganic gel comprising mixing specific non-fluorinated inorganic oxide precursors with particular carboxylic acids.
European Patent Application 0 574 928 A2 describes the synthesis of fluorosilicone resin by the hydrolysis of a perfluoroalkyl-containing silane of the formula F(CF.sub.2).sub.a CH.sub.2 CH.sub.2 SiY.sub.3, wherein Y is chlorine, bromine or C.sub.1 to C.sub.4 alkoxy, after being dissolved in an organic solvent and subsequently dripped into aqueous acid. Additional water or organic solvent is added thereafter and later an aqueous layer removed.
The process of the present invention concerns hydrolysis and condensation of inorganic oxide precursors in a fluorinated solvent. Fluorinated solvents have not previously been used for such processes due to their incompatability with water, catalysts and inorganic oxide precursors.
It is desirable to generate hybrid inorganic and fluoropolymer materials with very small inorganic domains (&lt;75 nm) so as to improve the durability of the fluoropolymer. It is well known that small inorganic particles can be generated via sol-gel chemistry. However, such chemistry is not practiced in perfluorinated solvent systems which are essential for dissolving said fluoropolymers.